A woman from Bracknell had her bathroom window set on fire from the outside at approximately 11:30pm on Friday, June 13.
Thames Valley Police are now appealing for witnesses to the arson which took place at a property in Hampden Crescent, Bracknell.
The victim, a woman in her thirties, did not sustain any injuries and the fire was extinguished by the fire service.
Police staff investigator Collette Gray said: “We believe that this fire was started deliberately and so are investigating it as an incident of arson.
“I am appealing for any witnesses or anyone with information to please come forward.
“The back of the property can be accessed from Blenheim Avenue, so if you have CCTV cameras or if you were driving in the area with a dash-cam, please check your recordings in case it has captured something that could assist our investigation.
“To contact us, call 101 or make a report on our website, quoting reference number 43250293666.
“Alternatively, you can provide information anonymously to the independent charity, Crimestoppers, by calling 0800 555 111 or via its website.”
